1. Field of the Invention
The present invention relates to towing accessories and, more particularly without limitation, to tow bars for towing a vehicle to be towed behind a towing vehicle.
2. Description of the Related Art
A tow bar is generally used for connecting a towing hitch apparatus of a vehicle to be towed, sometimes referred to herein as a towed vehicle, to a towing hitch apparatus of a towing vehicle. For applications wherein the towed vehicle will be towed at a speed sufficient to move with the flow of traffic on a public roadway, the tow bar, which connects the front end of the towed vehicle to the rear end of the towing vehicle, generally has two tow bar legs with the front ends of the tow bar legs forming the apex of an isosceles triangle and the rear ends of the tow bar legs spaced apart and forming the sides of the triangle. The triangular configuration causes the towed vehicle to closely track the towing vehicle, both along straightaways and around turns.
Tow bars for moving towed vehicles rapidly along public roadways must be designed to accommodate variations in attitude that operatively arise between the towing and towed vehicles, which variations are constantly and continuously changing. One such variation in attitude between the vehicles is the instantaneous elevation of the towing vehicle relative to the instantaneous elevation of the towed vehicle. A related variation in attitude between the vehicles is the instantaneous ascent/descent orientation of the towing vehicle relative to the instantaneous ascent/descent orientation of the towed vehicle. Both of these related variations in attitude can be accommodated by apparatus designed to accommodate rotations between the towing and towed vehicles about a transverse, horizontal axis, sometimes referred to as the “pitch” axis, see the “z”-axis in FIG. 1.
Another such variation in attitude between the vehicles is the instantaneous horizontal direction in which the towing vehicle is traveling relative to the instantaneous horizontal direction in which the towed vehicle is traveling, such as when the towed vehicle is being pulled around an unbanked corner for example. This phenomenon, sometimes referred to as “yaw”, can be accommodated by apparatus designed to accommodate rotations between the towing and towed vehicles about a vertical axis, see the “y”-axis in FIG. 1.
Finally, another such variation in attitude between the vehicles is the instantaneous sidewise tilt of the towing vehicle relative to the instantaneous sidewise tilt of the towed vehicle, such as the rocking motion which occurs when traversing uneven or rough pavement for example. This phenomenon, sometimes referred to as “roll”, can be accommodated by tow bar apparatus designed to accommodate rotations between the towing and towed vehicles about a longitudinal, horizontal axis, see the “x”-axis in FIG. 1.
During actual towing operations, all combinations of pitch, yaw and roll phenomena are continuously occurring and changing. Prior art is replete with tow bar designs that have been developed in an attempt to accommodate these phenomena, some of those designs being more successful than others. For example, a ball hitch/ball hitch socket combination securing a tow bar to a towing vehicle can theoretically accommodate all three of the pitch, yaw and roll phenomena. Although the ability of such a combination to accommodate yaw is encouraging, unfortunately the ability of such a combination to accommodate either pitch or roll is extremely limited, where failure to closely abide by those limitations can produce disastrous and even fatal results.
A commonly used arrangement involves using a conventional receiver hitch in combination with a square tube. Although such an arrangement may be convenient for connecting a tow bar to a towing vehicle, this type of connection by itself provides absolutely no ability to accommodate any one of the three pitch, yaw or roll phenomena. As a result, the tow bar and/or the connections between the tow bar and the towed vehicle must be relied upon to provide a solution for minimizing the potentially detrimental effects of these phenomena.
Prior art tow bars have utilized a variety of structures to accommodate the three axes of rotation between the towing vehicle and the towed vehicle. Due to the extreme operational and environmental conditions to which the tow bars are subjected, some tow bars leave much to be desired.
For many applications, an ability to conveniently store a tow bar on a towing vehicle is a desirable feature, such as storing the legs of the tow bar legs in a generally vertical orientation. Unfortunately, such as arrangement generally interferes with access to the rear of the towing vehicle. Other arrangements include storing the legs of the tow bar in a generally horizontal orientation. Unfortunately, both storing arrangements—vertically and horizontally—generally require the use of pins which can be easily lost or difficult to remove, or require structure which may be complicated, inconvenient, unreliable or unsafe. See, for example, U.S. Pat. No. Re. 35,482 to Andrew B. Johnson for “Towing Hitch” wherein locking pin 84 in combination with cotter pin 86 are needed to retain that tow bar in a storage position. Also see U.S. Pat. No. 5,765,851 to Richard A. Parent for “Self-Aligning Towing Apparatus” wherein pin 70 and locking pin 232 are needed to retain that tow bar in a storage position.
What is needed is a tow bar wherein the structure thereof can accommodates the three axes of rotation between the towing vehicle and the towed vehicle, and can provide simple, uncomplicated stowing on the towing vehicle without the need for a pin or other potentially unsafe or unreliable mechanism for enabling storage on the towing vehicle.